Pastes and Oils

Early humans also used primitive versions of sunscreen made from natural compounds. Red ochre, a type of claylike iron oxide, has been mixed with water and applied as a paste to the skin since the time of early Homo sapiens. This mixture was used for ceremonial reasons, but scientists believe it may also have served as a physical barrier against the sun. 

Ancient Egyptians, meanwhile, used skin treatments made from ingredients such as rice bran (which absorbs UV light), jasmine (to help repair sun-damaged skin), and lupine (believed to lighten the complexion). Ancient Greece had its own approach: Olive oil was commonly applied to the skin between 800 and 500 BCE. While it offered limited protection, modern studies have found it has a natural sun protection factor (SPF) of about 8 — enough to slightly reduce burning, though far lower than today’s common SPF 30 (the minimum recommended by dermatologists).

Like with ochre, other pastes were made from a variety of natural compounds, including mud and clay. These were used not only as camouflage or ceremonial decoration, but also as protection from the sun. Zinc oxide was used in India as early as 500 BCE, and water reeds and spices were turned into sunscreen by the Sama-Bajau peoples of Southeast Asia around 840 CE. Indigenous peoples in the Americas, meanwhile, used sunflower oil, pine needles, western hemlock bark, and deer fat, while thanaka, a mixture made from ground bark and water, has been used in Myanmar (formerly Burma) for more than 2,000 years. 

Masks

Over time, in some societies — including in ancient Egypt and later in Europe and parts of Asia — protecting the skin became a mark of social status. A pale complexion signaled that you could afford to avoid outdoor manual labor and instead spend your days indoors or in the shade. 

In Egypt, this desired look was achieved through use of parasols and topical skin treatments that blocked the sun. In Europe in the 16th century — particularly in France and England — upper-class women wore striking-looking visard masks to prevent sunburn and preserve that pale complexion. 

The visard mask was made of black velvet with a silk interior lining, and its only features were a slight protrusion for the nose and small holes for the eyes and mouth. The masks weren’t just eerie to look at, either — they were rather unsettling to wear. Most versions didn’t have straps and were instead held in place by a bead or button gripped between clenched teeth; the wearer couldn’t speak while the mask was on. 

By the early 1700s, visard masks had spread beyond the aristocracy, and beyond their intended purpose of preventing sunburns. Women of various social classes wore them, including sex workers, who often used them to discreetly enter public spaces such as theaters. In 1704, Britain’s Queen Anne even banned visard masks from the theater, but they’d already lost their status among the elite and eventually faded out of use.

Tannins and Trusty SPF

By the end of the 19th century, dermatologists confirmed that prolonged exposure to the sun’s UV rays could inflame or burn the skin, and scientists began experiments to develop effective and suitable topical sun protection. In 1878, Austrian physician Otto Veiel promoted tannins — natural compounds found in many plants — as viable sun protection, but they also discolored the skin. 

In 1891, a German doctor experimented with what was likely the first true attempt at a chemical sunscreen, a quinine-based ointment to treat skin sensitivity to sunlight. And in the early 1900s, German physician Paul Unna came up with another sunscreen precursor, a paste made of natural ingredients such as chestnut extract. Ultimately, these early products didn’t apply well, either discoloring the skin or going on too thick, and so the experiments to find a better solution continued.

It wasn’t until the mid-1900s that sunscreens began to resemble what we use today. In 1942, the U.S. military tapped the American Medical Association to study products or substances that could help protect soldiers from getting sunburned during particularly hot World War II Pacific campaigns. The solution was a thick, red, veterinary petroleum salve, also known as “red vet pet.” It was waterproof, durable, nontoxic, inexpensive, and, most importantly, relatively effective. 

Florida pharmacist Benjamin Green had served in the Air Force throughout the war, and in 1944, he began experimenting with ways to make the sticky substance more appealing. He added ingredients such as cocoa butter and coconut oil, creating a smoother, nicely scented lotion — the earliest version of what later became Coppertone. Throughout the 1950s and 1960s, sunscreen formulas continued to improve in texture and ingredients, offering broader protection against UVA and UVB rays, and by the 1970s and ’80s, sunscreen was widely marketed for sunburn protection and as a tanning aid.

Today, sun protection can be as subtle as a swipe of SPF lip balm or as advanced as UV-reflective clothing and tinted window film. The methods may have changed, but the instinct remains the same: When the sun beats down, we find ways to keep cool, stay covered, and avoid the burn.

Luckily, some enterprising minds were working on a better solution. In 1902, Alabama entrepreneur Mary Anderson was visiting New York City when she had an idea while riding the trolley. Trolley cars had windows and windshields long before autos, and on this particular ride she noticed her driver struggling to see through the sleet-slicked windshield. The driver tried a few things, including opening both windshield panes to peer between them, and getting out every few minutes to clear the windows. Inspired to solve this nuisance, Anderson sketched out an idea for a window-cleaning device: a hand-operated lever inside the vehicle that controlled a wiper on the outside. 

Anderson received a patent for her invention in 1903, but cars weren’t yet very popular — there were just under 33,000 registered vehicles in the U.S. at the time — and they didn’t all have windshields, so interest was slim. The patent expired without success in 1920, right around the time the automobile started to become a fixture of American life: Between 1919 and 1929, the number of passenger cars on U.S. roads skyrocketed from 6.5 million to 23 million. 

Other similar patents followed, and by about 1916, some of the cars that had adopted windshields also came equipped with wipers, but they were often optional, and were not yet widely used. That same year, however, Buffalo, New York, engineer John Jepson patented a simple windshield cleaner. It was similar in essence but more complex than Anderson's early designs. His consisted of spring-loaded arms that applied consistent pressure on both the top and bottom of the common horizontally split sections of windshields at the time.

The idea caught the attention of John Oishei, a local theater manager who vowed to improve driving visibility after hitting a bicyclist with his car while driving in the rain. He partnered with Jepson to market the device, branding it as the Rain-Rubber with the slogan, “Would YOU Drive Blindfolded?” 

The Rain-Rubber quickly gained traction, and by the mid-1920s, windshield wipers had become standard on cars from several manufacturers, including Cadillac and Ford. While wiper-related patents have continued to flood in by the hundreds each decade ever since, at their core, windshield wipers remain true to the simple concept Anderson thought up on that New York City trolley back in 1902 — a blade wiping away the rain.

Frederick McKinley Jones 

In 1938, Frederick McKinley Jones began designing a portable air-cooling unit for trucks. His invention ultimately revolutionized the transportation industry, with mobile refrigeration allowing trucks and railroad cars to safely transport perishable goods over long distances. As well as fundamentally changing food distribution, the invention also proved vital during World War II, allowing for the transportation and preservation of blood, medicine, and food for military use. 

In total, Jones earned more than 60 patents in his lifetime, and despite having minimal formal schooling, he became the first Black American to be awarded the National Medal of Technology.

Charles Richard Drew

Charles Richard Drew was a physician and surgeon who invented a method for the long-term storage of blood plasma in blood banks. During the early years of World War II, he organized and directed the blood-plasma programs of both the United States and Great Britain, saving thousands of lives. This led to a national blood-banking program led by Drew and the American Red Cross, and the introduction of  bloodmobiles and blood drives as we know them today. 

Drew also openly criticized policies that segregated the blood of African Americans from plasma-supply networks — an issue that saw him resign his position with the American Red Cross. It wasn’t until 1950 — the year of Drew’s death in a car accident — that the Red Cross stopped requiring the segregation of blood based on race. (Blood segregation remained in place in Southern states such as Arkansas and Louisiana until the late 1960s and early 1970s.) 

Marie Van Brittan Brown 

In the 1960s, Marie Van Brittan Brown, a nurse living in Jamaica, Queens, began to feel increasingly unsafe when home alone due to skyrocketing crime rates in the area. So, with help from her husband Albert L. Brown, an electronics technician, she began inventing what became the first home security system with video surveillance. 

Completed in 1966 and patented three years later, the security system consisted of four peepholes, a sliding camera, television monitors, and two-way microphones. It also incorporated a remote control that allowed for locking and unlocking the door at a safer distance, and an emergency button that would send an alarm directly to the police or security. While not manufactured on a large scale due to high production costs, the invention gained widespread recognition and formed the foundation of modern CCTV and home security systems.

Patricia Bath 

Ophthalmologist Patricia Bath revolutionized cataract surgery when she invented laserphaco, a device and technique that could perform all the necessary steps of cataract removal. Overall, the laser device allowed for less painful and more precise treatment of cataracts, and could help restore the sight of individuals who had been blind for more than 30 years. The device is now used worldwide and has improved the vision of millions of people. When laserphaco was patented in 1988, Bath became the first Black female physician to receive a medical patent in the United States.

In 1916, Sears introduced the feature that is most often associated with its mail-order homes: ready-cut lumber. Cut in the factory to fit, the lumber did not require any trimming before it was nailed together. This allowed for cost savings for the buyer as fewer carpentry hours were needed (a savings Sears estimated at 40%), and it was advantageous for the company as well: Sears was able to purchase lumber in more economical lengths, as well as use second-grade lumber and convert it to first-grade via trimming. The trimmed pieces were often repurposed for other materials — with the timber waste removed, freight costs were substantially reduced. To further encourage sales, Sears reintroduced its own mortgage program, which had originally been active from 1911 to 1913.  

In 1919, the end of World War I brought with it the end of wartime building restrictions. A housing boom ensued, spurred on by the return of soldiers. Sears introduced three tiers of Modern Homes: Simplex Sectional (small two-room structures), Standard Built (less-insulated homes best suited for warmer climates), and Honor Bilt, high-end homes that featured amenities such as cypress siding, kitchens with white tile sinks and enameled cupboards, and “Air-Sealed Wall construction.” Sales from 1912 to 1920 totaled $29,160,000, at a profit of $3,377,000. During that same time frame, around $3.8 million in mortgage loans were written. 

During the 1920s, Sears set its sights on maximizing the booming housing market. The company had opened its first sales office specifically for Modern Homes in Akron, Ohio, in 1919, and in 1920, it built a Philadelphia plant that became the base of Sears’ East Coast operations. In 1921, sales offices opened in Pittsburgh, Cleveland, Cincinnati, and Dayton, followed by sales offices in Chicago, Philadelphia, and Washington the following year. 

The offices used the Sears mortgage program as a major selling tactic, steering buyers toward mortgages, and the company’s loan policy became more and more lenient in response to sales pressure. Accordingly, sales were booming, increasing from an average of 125 units shipped per month in 1920 to 326 units in May 1926 from the Cairo plant alone. But by 1926, mortgage loans represented 97% of sales. 

The year 1929 was set to be a banner year for Sears Modern Homes. The department had sold 49,000 houses from its inception up to that point. It was averaging 250 units shipped per month just from its Cairo plant, and had a sales staff of 350 people in 48 different offices throughout the country. The $12,050,000 in sales for 1929 represented the highest total the department had ever had. But when the stock market crashed in October 1929, eventually plunging the United States into the Great Depression, Sears Modern Homes was one of the many businesses the bottom fell out of.

The decline was swift. The Sears annual stockholder report for 1932 plainly stated, “Since September 1931, [the Modern Homes department] has operated at a loss. Its sales declined over 40% in our fiscal year, with resulting losses of $81,154,984 during the year.” Two years later, the annual report relayed the dire state precipitating the end of the department: “About $11,000,000 in mortgages were liquidated during the year and the Modern Homes Department was discontinued.” 

The department was reopened in 1935 under a different configuration, selling prefab houses by Chicago’s General Houses, Inc., and the Modern Homes catalog continued to be issued until 1940. Modern-day Sears house enthusiasts cite 1942 as the final year a Sears mail-order home was built, as orders from the final 1940 catalog continued to be filled in the year or so after the catalog was published. Unfortunately, Sears’ own records of home sales were destroyed, complicating a definitive date.

Though the 1929 stock market crash and Great Depression provide a tidy explanation for the beginning of the end of the Sears Modern Home department, historians Boris Emmet and John E. Jeuck made a different assessment in their seminal 1950 book, Catalogues and Counters: A History of Sears, Roebuck & Company. The book points out the unsustainability of the business model. Increased sales thresholds for Modern Homes necessitated building (or acquiring) more manufacturing plants to handle the increased production needs. The costly production facilities required investments in shipping and transportation, too, along with an increasingly growing and complex service organization to support the business.

The push for sales meant relying on ever more lenient mortgages and approving otherwise undesirable credit risks, creating what Emmet and Jeuck called an “ever increasing and ever more unsound mortgage receivable structure.” Ultimately, the business was simply not scalable: As sales increased, profit margins declined. The peak profit margin for Modern Homes was 15% in 1919 and 1920. It dropped to an average of approximately 10% from 1921 to 1926, and fell under 5% by 1928. The narrowing margins left the business unable to weather a slowdown in sales, let alone a large economic crisis. As Emmet and Jeuck wrote, “At any time subsequent to 1926, the onset of a [sales decline] would probably have developed losses comparable to those which actually were incurred after 1929; the condition was inherent in the structure.”

Heeding Haldane’s recommendation, British miners began taking canaries into the coal mines — carried in small metal or wooden cages — to detect the presence of odorless carbon monoxide. If the canary showed any signs of distress (or if it suddenly died), it was a clear sign to the miners that conditions were unsafe and the mine should be evacuated. The use of canaries in this way is perhaps the most common example of what is known as a sentinel species, a term applied to animals or plants that serve as harbingers of danger to human health or the wider environment. 

It wasn’t long before the use of canaries in coal mines became commonplace not only in Britain but also in the United States and Canada. The birds became such a trusted part of the mining process — part of the team, you could say — that miners were known to treat their avian companions almost as pets. In some cases, special cages were designed for the canaries that could be used to resuscitate the poor little birds should they succumb to noxious gases. These metal-and-glass cages were fitted with a small oxygen tank. If the canary inside began to show signs of carbon monoxide poisoning, the cage door was closed and a valve opened to revive the bird with a fresh supply of oxygen.

Canaries were used in British coal mines for almost a century. Then, in 1986, hundreds of canaries breathed a collective sigh of relief when Britain announced that the use of birds in coal mines would stop, to be replaced with modern detectors, often known as “electronic noses.” But to this day, canaries retain their connection with coal mining, as much a symbol of the profession as coal-blackened faces, hard hats, and pickaxes. The canary’s role in the mines was so significant that it also became ingrained in the English language: The common idiom “a canary in the coal mine” is still used to refer to something that gives an early warning of danger. 

Precision Medical Instruments

The Romans were great pioneers in the field of surgery. We know from archaeological evidence — including well-preserved artifacts found in the buried remains of Pompeii and Herculaneum — that the Romans used precision medical instruments including bone forceps, catheters, obstetrical hooks, scalpels, and surgical scissors. The level of technology found in some of these tools is not so far from their modern counterparts. The Roman version of the vaginal speculum, for example, did not change significantly until the 20th century. The Romans also had a medical military corps with specialized field surgeons who were tasked with keeping the legions fit, healthy, and alive. 

Underfloor Heating

Heated floors might seem like a modern luxury, but the Romans started using them 2,000 years ago. Ancient Romans used an underfloor heating system known as a hypocaust, which drew in hot air from a wood-burning furnace outside the house and channeled it into a chamber below the floor. This not only warmed the floor itself but radiated heat throughout the home. Many examples of hypocausts can still be found in the foundations of villas and townhouses in Roman centers in Germany and England, where cold winters would have made the toasty floors especially inviting. 

The Shopping Mall

Markets have long been prevalent throughout the world as a gathering place for people to sell and buy all sorts of goods and produce. But the first permanent and covered shopping mall was likely built by the Romans: Trajan's Market (Mercatus Traiani), constructed between 100 and 110 CE. Made of red brick and concrete, it had six levels that housed around 150 different shops, as well as government offices and living accommodations. A street on the upper level, meanwhile, was named Via Biberatica after the Latin word for “drink,” suggesting that even the Romans needed to unwind after a hard day’s shopping. 

Our Calendar

Most of the world now uses the Gregorian calendar, first introduced in 1582 by Pope Gregory XIII. But credit for the modern calendar should really be given to the Romans. The Gregorian calendar is based on the much earlier Julian calendar (which itself owed a lot to the Egyptian solar calendar), introduced by Julius Caesar in 45 BCE. The calendars share many similarities, though one of the main differences is the treatment of those pesky leap years. The Gregorian calendar handles them more precisely, resulting in a discrepancy between the two calendars that is currently 13 days, and will become 14 days in 2100.